Nice looking boat! Welcome to the group - there is a wealth of information available from the people here!!
I'm unfortunately not as great a resource as some of them, but in looking at your pictures, there is one item that I might have a small hint for you with, and that is that some models of the Evinrude Lark had a "push-pull" (my words for it) fuel system in where one of the lines to the fuel tank is an air pressure hose which they used instead of the more common vacuum pump that most of us are used to.
I have an old Lark from my Dad that gave me fits last year and I never did get it to work right before putting the project aside for another date. But I can tell you that problems with system are very common to make it run very "clunky," if at all, and commonly makes it look like spark problems.
Good luck with your restoration!